Not working

I workout 6 out if the 7 days if the week in general, and I eat pretty healthily,staying below 1200 calories almost everyday. I've only lost 5 pounds in about a month and that was because I got sick and stopped eating pretty much everything. I've always been so active that my body is just used to working out that much, and I can't lose any weight because it can't a tell a difference. What should I do? Nothing is working.